Immobilization of psicose-epimerase and a method of producing D-psicose using the same

Abstract

The present invention relates to a method of successively producing D-psicose from D-fructose or D-glucose by using a psicose-epimerase derived from Agrobacterium tumefaciens which is expressed in a food safety form.

The invention claimed is: 
     
       1. A method of preparing D-psicose from D-fructose by using a psicose-epimerase isolated from  Agrobacterium tumefaciens , and expressed in a GRAS (generally accepted as safe) strain, wherein the GRAS strain is  Corynebacterium glutamicum  KCCM 11046, said method comprising steps of:
 expressing the psicose-epimerase isolated from  Agrobacterium tumefaciens  in the GRAS strain; and 
 preparing D-psicose from D-fructose by using the expressed psicose-epimerase. 
 
     
     
       2. The method of  claim 1 , wherein the psicose-epimerase used in the preparation of D-psicose is contained in a culture of the GRAS strain or separated from the culture. 
     
     
       3. The method of  claim 1 , wherein the psicose-epimerase isolated from  Agrobacterium tumefaciens  has the amino acid sequence of SEQ ID NO: 1. 
     
     
       4. The method of  claim 1 , wherein the step of preparing D-psicose comprises the step of immobilizing the psicose-epimerase onto a carrier. 
     
     
       5. The method of  claim 4 , wherein the carrier is sodium alginate. 
     
     
       6. The method of  claim 4 , wherein the method further comprises the steps of packing a column with the carrier onto which the psicose-epimerase is immobilized and supplying the packed column with a D-fructose solution. 
     
     
       7. A method of preparing D-psicose from D-glucose, wherein psicose-epimerase is isolated from  Agrobacterium tumefaciens  and expressed in a GRAS (generally accepted as safe) strain, wherein the GRAS strain is  Corynebacterium glutamicum  KCCM 11046, comprising the step of immobilizing a psicose-epimerase and a D-glucose isomerase onto carriers. 
     
     
       8. The method of  claim 7 , wherein the expressed psicose-epimerase is contained in a culture of the GRAS strain or separated from the culture. 
     
     
       9. The method of  claim 8 , wherein the GRAS strain is a strain transformed with a recombinant vector including a gene encoding a psicose-epimerase. 
     
     
       10. The method of  claim 8 , wherein the psicose-epimerase has the amino acid sequence of SEQ ID NO: 1. 
     
     
       11. The method of  claim 7 , wherein the carrier is sodium alginate. 
     
     
       12. The method of  claim 7 , wherein the method further comprises the steps of packing a column with the carriers onto which the psicose-epimerase and the D-glucose isomerase are immobilized and supplying the carrier-packed column with a D-fructose solution. 
     
     
       13. The method of  claim 12 , wherein each of the carriers onto which the psicose-epimerase and the D-glucose isomerase are immobilized, respectively, is packed into a separate column, and the two columns are connected in communication with each other.